Re: Quiet Airliners of the Future?

On Wed, 14 Sep 2005 23:46:10 GMT, Chris Kennedy <chris@xxxxxxxxxxxxx>
wrote in <6D2We.13676$p%3.58452@xxxxxxxxxxxxxxxxx>::

>but the
>issue is with uncommanded roll as a consequence of turbulence.

If the aircraft is not maneuvering (or even if it were), the
electronically augmented control system would detect an incipient wing
displacement before a human could detect it, and issue the appropriate
control input to counter it. These commands would occur so rapidly as
to be virtually undetectable by the occupants.

Think of the electronic suspension systems available on some of
today's automobiles*. They are capable of providing a smooth ride
over the roughest of roads by sensing body dip, and immediately
extending the suspension to prevent further excursions. These
corrections happen in milliseconds; it verges on magic.

>> If the roll
>> rate is brisk, there may be some increase in G felt by passengers in
>> the rising wing, and decrease in G felt by those in the descending
>> wing, but with today's computerized fly-by-wire control systems, all
>> these concerns could be largely eliminated in nearly all cases.
>
>Unless you're suggesting that fly by wire could automatically limit the
>roll rate to limit the acceleration felt by outboard passengers I'm
>unclear how it would address the problem.

I'm confident that an electronic control system could dampen all but
the most severe turbulence induced excursions, in addition to seeing
that the commanded roll rate was strictly met.

>There's also the roller coaster effect -- being on the high side and
>looking down the width of the cabin at what seems like an exaggerated
>angle -- but I suppose one could deal with that with dividers of some
>sort.

Exactly. First class would be along the longitudinal axis with coach
toward the wing tips with obscure partitions separating them.

>There's also the issue of just how one evacuates such an aircraft.

Umm... Crashworthyness would be an issue less amenable to resolution
than evacuation.

>As I said, good for freight, but I'd take some convincing before I flew
>in one.

In the event of an in flight electrical failure disabling the
electronic control augmentation, it could get "interesting." What
does Airbus use to overcome that issue?

>Of course I'm not too thrilled with the idea of riding in an
>A380, either.

Right. In the event of a 800+ passenger stampede, one would likely be
trampled before he could clear the aircraft. :-)




* http://tinyurl.com/ah236
http://www.edmunds.com/insideline/do/Features/articleId=100444
The optional F55 Magnetic Selective Ride Control suspension
adjusts the shock damping rates instantly in response to changing
conditions. http://www.corvettecenter.com/magneticrc.htm

http://www.modernracer.com/history/chevroletcorvettec6history.html
optional F55 Magnetic Selective Ride Control suspension features
magneto-rheological dampers able to detect road surfaces and
adjust the damping rates to those surfaces almost instantly for
optimal ride and body control. Magnetic Ride Control debuted on
the 2003 50th Anniversary Edition Corvette, and is the world?s
fastest reacting suspension, replacing mechanical valves with
nearly instantaneous reactions of magneto-rheological fluid. The
system has been improved for the 2005 Corvette, allowing drivers
more differentiation in character between the system?s two
settings, ?Tour? and ?Sport.?
.

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